Add subject pattern configurable option

[antode]

Q	A
Branch	master
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	no
Documented?	yes
Fixed tickets

I work in a Russian-speaking team and type/scope checks fails when the subject is written in only Russian.
it would be great if we can define type_scope_conventions.subject_pattern like:

type_scope_conventions:
  - types: []
  - scopes: ~
  - subject_pattern: >-
      ([a-zA-Zа-яА-Я0-9-_ #@'\/\"]+)

[veewee]

Nice addition, thanks!